EP1084588B1 - Acoustic damping material - Google Patents
Acoustic damping material Download PDFInfo
- Publication number
- EP1084588B1 EP1084588B1 EP99955386A EP99955386A EP1084588B1 EP 1084588 B1 EP1084588 B1 EP 1084588B1 EP 99955386 A EP99955386 A EP 99955386A EP 99955386 A EP99955386 A EP 99955386A EP 1084588 B1 EP1084588 B1 EP 1084588B1
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- EP
- European Patent Office
- Prior art keywords
- acoustic
- sheet
- speaker system
- acoustic damping
- damping material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
- H04R1/2869—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself
- H04R1/2876—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding
- H04R1/288—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding for loudspeaker transducers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
- H04R1/2869—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself
- H04R1/2884—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of the enclosure structure, i.e. strengthening or shape of the enclosure
- H04R1/2888—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of the enclosure structure, i.e. strengthening or shape of the enclosure for loudspeaker transducers
Definitions
- This invention relates to acoustic damping material. More particularly, this invention relates to acoustic damping material for use in various acoustic devices, such as acoustic speaker systems and acoustic damping panels.
- Acoustic speaker systems generally include at least one acoustic speaker mounted to a speaker enclosure.
- the speaker converts electric energy into acoustic energy over a particular frequency range.
- the conversion of electric energy into acoustic energy is limited by the mechanical constraints of the speaker and its enclosure.
- an electric current energizes an electromagnet that is fixed to a lightweight flexible surface, producing an electromagnetic field.
- This field interacts with another magnetic field produced by a permanent magnet fixed to a frame holding the flexible surface.
- the interaction between the fields produces a force which drives the surface to vibrate at the frequency of the electric signal, thereby producing acoustic energy.
- DE-A-33 17 273 relates to a silencer or noise suppressor intended to achieve improved low frequency damping and adapted for ventilation ducts or ventilation apparatus.
- Said silencer comprises one or more porous elements, e.g., of mineral wool, serving as resistive sound absorber and arranged on a duct or apparatus casing, solely as wall cladding as baffles swept over by the air stream, wherein one or more of the porous elements have its upstream and downstream ends surrounded by substantially unperforated sheet-like material, preferably metal sheets.
- JP-A-10 061 057 relates to a vibration-damping sheet for a folded plate roof of a resin composition consisting of a styrene-isoprene block polymer, inorganic fine particles and a polyolefin resin.
- the extrusion-molded vibration-damping sheet is laminated on a steel plate, and secondarily corrugated on a steel plate, and the folded plate roof backed by the vibration-damping sheet is formed.
- FR-A-2 372 566 relates to an acoustic damping system comprising an enclosure in which a noise absorbing material is located and two speakers for higher and lower sounds.
- a panel is mounted within the enclosure with one side facing the back panel of the enclosure. Between the panels a highly compressible material is located, e.g. balls of glass wool or kapok.
- acoustic speaker system enclosures An important disadvantage of acoustic speaker system enclosures is the large physical size required to ensure a balanced and efficient low frequency response.
- the primary reason for using a large enclosure is to provide a sufficient volume of air against which a woofer can freely vibrate.
- Small enclosures contain small volumes of air which restrict the vibratory motion of the woofer.
- Acoustic dampening materials such as fiberglass, wool, and synthetic polyester fibers (such as those sold under the trademark DACRON®, by E. I. du Pont de Nemours & Company, of Wilmington, Delaware), are often used to diminish the enclosure size requirement. Unfortunately, however, because of these materials' low acoustic absorption, the use of these materials can not substantially reduce the size of the enclosure and simultaneously ensure a balanced low frequency response.
- the enclosure absorbs it, and subsequently releases it in the form of acoustic energy at different undesired frequencies, including, possibly, undesirable harmonics of desirable acoustic frequencies.
- Acoustic damping materials can also be useful for absorbing sound in substantially enclosed spaces, such as sound recording rooms and areas that are subject to undesirable noise.
- One method for absorbing sound includes mounting acoustic damping panels on one or more walls of the enclosed space.
- a disadvantage of conventional acoustic damping materials, which are often made from foamed materials, is that such materials are generally expensive and relatively inefficient.
- an acoustic damping material which includes at least one resilient sheet.
- Each sheet has a first side and a second side. At least a first portion of one of the first and second sides and a second portion of one of the first and second sides face each other to form a multi-layered structure.
- the resilient sheet consists of a polyolefin, and more particularly may comprise polyethylene.
- the sheet preferably has a thickness of less than about 5 mils (about 0.13 mm), and most preferably has a thickness of less than about 1.5 mils (about 0.038 mm).
- the acoustic damping material of this invention may be used to make an acoustic speaker system with an exceptionally flat frequency response.
- An acoustic speaker system according to this invention at least includes a system enclosure, an acoustic speaker mounted to the enclosure, and acoustic damping material (according to this invention) inside the enclosure.
- the acoustic damping material of this invention may also be used to make an acoustic damping panel.
- the panel includes a frame and acoustic damping material fixed to the frame.
- the acoustic damping material again includes at least one resilient sheet arranged in a multi-layered fashion.
- the present invention is directed to an acoustic damping material.
- the material When used in an acoustic speaker system, the material provides an exceptionally flat frequency response, especially at low frequencies.
- the acoustic damping material of this invention is made from at least one resilient sheet, which is preferably arranged to form a multi-layered acoustic damping structure.
- the resilient sheet consists of a polyolefin.
- the polyolefin is polyethylene.
- the sheet preferably has a thickness of less than about 5 mils (about 0.13 mm), and most preferably has a thickness of less than about 1.5 mils (about 0.038 mm).
- the resilient sheet has a first side and a second side. At least a first portion of one of said first and second sides and a second portion of one of said first and said second sides face each other to form a multi-layered structure.
- one or more sheets may be deformed to create a multi-layered structure.
- a sheet may be folded, rolled, twisted, or simply crushed with no particular regularity.
- two or more sheets may be rolled, folded, or twisted together if desired.
- pockets, or strata, of a compressible material e.g., air are located between adjacent layers.
- Resilient multi-layered structures have been shown to have unusually high acoustic opacity.
- the high acoustic opacity of these multi-layered structures is believed to result from a combination of the high compressibility of the air pockets and the resilient nature of the individual sheets.
- the acoustic opacity of the material is improved when a large number of layers is used and when those layers are oriented substantially perpendicular to the acoustic waves being blocked.
- sheets used to make the acoustic damping material of this invention are entirely different from known fibrous acoustic damping materials.
- Sheets may form flexible barriers that may force incident air in a direction that preferably is substantially perpendicular to the direction of the incident sound wave.
- fibers, to some degree, also redirect sound waves, fibers do not form highly flexible barriers to the passage of sound waves.
- the acoustic damping material of this invention may be used to make an acoustic speaker system with an exceptionally flat frequency response, especially at low frequencies.
- a system includes a system enclosure, an acoustic speaker mounted to the enclosure, and acoustic damping material (made according to this invention) inside the enclosure. Any number of acoustic damping structures can be used inside the enclosure.
- the acoustic damping material is deformed to have a cavity that is adapted to receive the rear side of the speaker.
- the acoustic damping material made according to this invention can be used to make other types of acoustic damping structures, such as acoustic damping panels.
- An acoustic damping panel at least includes a frame and acoustic damping material according to this invention that is fixed to the frame. The surface area of the panel may be increased by constructing a frame that is not flat.
- FIG. 1 shows resilient sheet 100 that may be used to make an acoustic damping material in accordance with this invention.
- Sheet 100 is preferably deformed as described below to create a multi-layered acoustic damping structure.
- two or more sheets may be used together to create a multi-layered structure in accordance with this invention.
- Resilient sheets are preferably made from any substantially resilient polymer, which may include one or more copolymers.
- One type of polymer that can be used in accordance with this invention is a polyolefin.
- the polyolefin is polyethylene.
- a single sheet can have a substantially uniform composition, but can also be a laminate -- i.e., a plurality of substantially parallel layers whose adjacent surfaces are substantially bonded together.
- a resilient sheet used to make the acoustic damping material according to this invention preferably has a thickness of less than about 5 mils (about 0.13 mm), and most preferably has a thickness of less than about 1.5 mils (about 0.038 mm).
- a resilient sheet used to make the acoustic damping material according to this invention may be substantially nonporous to air at about atmospheric pressure (i.e., about 1 atm (about 101.3 kPa)).
- resilient sheets examples include plastic wraps sold under the trademarks Handi-Wrap®, by DowBrands L.P., of Indianapolis, Indiana and Franklin WrapTM, by Franklin Industries, L.L.C., of Brooklyn, New York.
- Other examples include Clear Food Wrap, by Pathmark Stores, Inc., of Woodbridge, New Jersey, Saran Wrap, by DowBrands L.P., Indianapolis, Indiana, Reynolds® Plastic Wrap, by Reynolds Metals Company, of Richmond, Virginia, and Glad® Cling Wrap, by First Brands Corporation, of Danbury, Connecticut.
- Resilient sheet 100 has two sides.
- Acoustic damping material according to this invention can include one or more sheets, each of which have a first side and a second side. At least a first portion of one of the first and second sides and a second portion of one of the first and second sides face each other to form a multi-layered structure. For example, this means that different portions of (1) one side of one sheet, (2) opposite sides of one sheet, or (3) sides of two different sheets, may face each other.
- single sheet 100 is deformed into a multi-layered structure.
- FIG. 2 shows one embodiment of this invention in which sheet 100 is folded to produce folded structure 110.
- FIG. 3 which is a cross-sectional view of structure 110
- portions 102 and 104 both of which are portions of a first side of sheet 100
- 116 and 118 both of which are portion of a second side of sheet 100
- both portions in any one pair of facing portions are from the same side of sheet 100, with alternating pairs being from different sides of sheet 100.
- a first way includes repeatedly folding sheet 100 to produce flattened roll structure 120, shown in FIG. 4.
- FIG. 5 shows a cross-sectional view of structure 120, including particularly portions 122 and 124 (both of which are portions of one side of sheet 100), which face each other, as well as portions 126 and 128 (each of which is a portion of a different side of sheet 100), which also face each other.
- portions 122, 124 of the same side of sheet 100 face each other, on this embodiment every pair of facing portions includes one portion from each side of sheet 100.
- Air 109 or any other highly compressible material, is located between the facing portions.
- FIG. 7 shows a cross-sectional view of roll 130, including particularly portions 132 and 134 (each of which is a portion of a different side of sheet 100), which also face each other.
- every pair of facing portions includes one portion from each side of sheet 100.
- air 129, or any other compressible material substantially fill the space between facing portions.
- a third way that sheet 100 can be deformed includes both folding and rolling it to create hybrid structure 140, as shown in FIG. 8.
- Structure 140 includes adjacent layers that face each other (see, e.g., FIG. 9, portions 142 and 144), which are substantially separated by layers of a compressible material (even though facing portions may be in physical contact).
- Acoustic damping material according to any of the embodiments shown in FIGS. 1-11 can also be deformed by twisting one or more sheets into twisted structure 150, as shown in FIGS. 10 and 11.
- multiple sheets may be used in any number of ways to form multi-layered structures.
- structure 130 is formed by rolling a single sheet, it will be appreciated that two or more sheets may be rolled together if desired.
- pockets of air or any other compressible material
- the pockets are substantially trapped between the layers. It should be noted, however, that at least some of the pockets are in fluid communication with one another so that the air can travel therebetween. Furthermore, the pockets may be in fluid communication with the atmosphere through one or more ports in the enclosure.
- the unusually high acoustic opacity of these multi-layered structures is believed to result from a combination of the high compressibility of the air pockets and the highly resilient nature of the individual layers. Accordingly, it is believed that the air pressure between the layers should not be substantially different from the atmospheric pressure during operation of the acoustic damping material. When the air pressure between adjacent layers (i.e., in the pockets) is substantially different from atmospheric pressure, that difference may increase the acoustic coupling between adjacent layers, which in turn may decrease the acoustic damping efficiency of the material. Also, the acoustic opacity of the material is improved when a large number of layers, each of which may be formed from the same or different sheets, is used and when those layers are oriented substantially perpendicular to the acoustic waves being blocked.
- the acoustic damping material of this invention may be used to make an acoustic speaker system with an exceptionally flat frequency response, especially at low frequencies.
- An acoustic speaker system constructed according to this invention also exhibits excellent dynamic response, including a 20% improvement in attack rate and a 30% improvement in decay rate over similar speaker systems using conventional acoustic damping material.
- An acoustic speaker system includes a system enclosure, an acoustic speaker mounted to the enclosure, and acoustic damping material made according to this invention inside the enclosure.
- the acoustic damping material used in this system is the same as described above.
- Additional acoustic components, such as enclosure ports for providing fluid communication between the acoustic damping material and the atmosphere and additional acoustic speakers, may also be added to the acoustic speaker system as desired.
- FIG. 12 shows a cross-sectional view of acoustic speaker system 200, which is constructed according to the principles of this invention.
- Acoustic speaker system 200 includes preferably spherical enclosure 210, speaker 220, and acoustic damping material 230.
- Acoustic damping material 230 includes one type of acoustic damping structure 232, although any number of acoustic damping structures can be used, as described below.
- Acoustic damping material 230 can be formed from one or more resilient sheets. These sheets can then be deformed into at least one multi-layered structure, such as the elongated structures shown in FIGS. 2-11.
- Acoustic damping material 230 which is inside enclosure 210 and behind acoustic speaker 220, may be placed in enclosure 210 in any way.
- material 230 may simply be loaded into enclosure 210 with no particular arrangement (not shown), or in any desired arrangement.
- material 230 may be wrapped in a spiral fashion as shown in FIGS. 12-14.
- acoustic damping material 230 can be deformed into a spherical structure having cavity 236, which has surface 237 that substantially conforms to, or adapted to receive, rear side 221 of acoustic speaker 220.
- rear side 221 has a conical shape
- material 230 can be adapted (e.g., toroidally wrapped) to receive that rear side.
- enclosure 210 can have other shapes. If enclosure 210 were cubical, for example, acoustic damping material 230 would preferably be deformed to have a substantially cubical shape, but the cavity would still be adapted to received the conical rear side 221 of speaker 220.
- TABLES I and II compare the frequency responses of two types of acoustic speaker systems.
- the first type of system was structurally substantially identical to system 200, but used conventional acoustic damping material (i.e., fiberglass wool).
- the second type of system was system 200, which used an acoustic damping material according to this invention (i.e., polyolefine film).
- the acoustic speaker systems included a 12" (30,48cm) diameter spherical enclosure and a 6" (15,24cm) diameter woofer (effective enclosure volume was about 0.47 ft 3 (ca. 0,0133 m 3 ).
- TABLE I lists experimental results obtained using a sealed enclosure and TABLE II lists experimental results obtained using a ported enclosure.
- Tables I and II reveal that the frequency responses of both the sealed and ported acoustic speaker systems, respectively, are dramatically improved, especially at the low end of the frequency range (i.e., between about 20 Hz and about 50 Hz). And, in the case of the sealed system, the improved frequency response is apparent at even higher frequencies (i.e., up to about 90 Hz). Moreover, while the resonant frequencies of both acoustic systems were identical (i.e., about 57 Hz), the Q values of those resonances in the systems filled with polyethylene film (according to this invention) were substantially reduced.
- acoustic speaker systems at least partially filled with polyethylene film are not as easily quantifiable. These improvements include better acoustic transparency, clarity, and imaging. It was also noticed that the acoustic damping material of this invention improves electric-acoustic energy conversion efficiency, especially at low electric power levels.
- FIG. 15 shows a cross-sectional view of another acoustic speaker system 300, which can also be constructed according to this invention.
- system 300 also includes enclosure 310, speaker 320, and acoustic damping material 330.
- acoustic damping material 330 which is used in system 300 (shown in FIG. 15), includes two types of acoustic damping structures.
- the first type of acoustic damping structure is deformed into coiled (i.e., toroidal) acoustic damping structure 332, which is placed adjacent to and behind speaker 320.
- Coiled structure 332 is multi-layered and can be made, for example, from one or more of the acoustic damping materials shown in FIGS. 2-11 and described above.
- Structure 332, as shown in FIG. 15, is made from an elongated roll structure, similar to the one shown in FIGS. 6 and 7.
- the second type of acoustic damping structure, folded structure 334 preferably fills the remainder of enclosure 310.
- Structure 334 also is deformed into layers, but the layers of structure 334 are preferably formed by folds in the resilient sheet, similar to structure 110.
- a compressible material such as air fills the space between layers.
- the layer density remote from enclosure inner surface 311 e.g., at point 312
- the layer density adjacent inner surface 311 e.g., at point 313).
- acoustic speaker system 300 shows only two acoustic damping structures 332 and 334, any number of structures can be used in accordance with this invention. Also, regardless of the number of structures used, the portions of the sheet(s) are preferably, to the greatest extent possible, substantially parallel to, or follow the contours of, enclosure internal surface 311 and/or the rear side of acoustic speaker 320. It should also be understood that the particular arrangements of the damping materials shown in FIGS. 12-15 may be altered as desired.
- Enclosure internal surface 311 can have any shape, including substantially ellipsoidal, substantially spherical, substantially cylindrical, substantially polygonal, and any combination thereof, but is preferably substantially spherical.
- acoustic damping material according to this invention can be used to make other types of acoustic damping structures, such as acoustic damping panels. Acoustic damping panels can be useful for absorbing sound in substantially enclosed spaces, such as sound recording rooms and areas that are subject to undesirable noise. Acoustic damping panel 400 is shown in FIGS. 16 and 17 and is constructed in accordance with the principles of this invention. Panel 400 includes frame 410 and acoustic damping material 420, which is preferably fixed to frame 410 by any convenient means, such as staples or adhesive. Material 420 is the same acoustic damping material described above with reference to FIGS. 1-11.
- acoustic damping material 420 includes at least one resilient sheet and is arranged in a multi-layered fashion.
- the frame used to make the acoustic damping panel may not be flat. In that case, the surface area of the panel can be increased.
- a general purpose acoustic damping material has been provided.
- the acoustic damping material can be used wherever an acoustic damping effect is desirable.
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Abstract
Description
- This invention relates to acoustic damping material. More particularly, this invention relates to acoustic damping material for use in various acoustic devices, such as acoustic speaker systems and acoustic damping panels.
- Acoustic speaker systems generally include at least one acoustic speaker mounted to a speaker enclosure. The speaker converts electric energy into acoustic energy over a particular frequency range. The conversion of electric energy into acoustic energy is limited by the mechanical constraints of the speaker and its enclosure. For example, in conventional electromagnetic speakers, an electric current energizes an electromagnet that is fixed to a lightweight flexible surface, producing an electromagnetic field. This field interacts with another magnetic field produced by a permanent magnet fixed to a frame holding the flexible surface. During operation, the interaction between the fields produces a force which drives the surface to vibrate at the frequency of the electric signal, thereby producing acoustic energy.
- DE-A-33 17 273 relates to a silencer or noise suppressor intended to achieve improved low frequency damping and adapted for ventilation ducts or ventilation apparatus. Said silencer comprises one or more porous elements, e.g., of mineral wool, serving as resistive sound absorber and arranged on a duct or apparatus casing, solely as wall cladding as baffles swept over by the air stream, wherein one or more of the porous elements have its upstream and downstream ends surrounded by substantially unperforated sheet-like material, preferably metal sheets.
- JP-A-10 061 057 relates to a vibration-damping sheet for a folded plate roof of a resin composition consisting of a styrene-isoprene block polymer, inorganic fine particles and a polyolefin resin. The extrusion-molded vibration-damping sheet is laminated on a steel plate, and secondarily corrugated on a steel plate, and the folded plate roof backed by the vibration-damping sheet is formed.
- FR-A-2 372 566 relates to an acoustic damping system comprising an enclosure in which a noise absorbing material is located and two speakers for higher and lower sounds. A panel is mounted within the enclosure with one side facing the back panel of the enclosure. Between the panels a highly compressible material is located, e.g. balls of glass wool or kapok.
- An important disadvantage of acoustic speaker system enclosures is the large physical size required to ensure a balanced and efficient low frequency response. The primary reason for using a large enclosure is to provide a sufficient volume of air against which a woofer can freely vibrate. Small enclosures, however, contain small volumes of air which restrict the vibratory motion of the woofer. Acoustic dampening materials such as fiberglass, wool, and synthetic polyester fibers (such as those sold under the trademark DACRON®, by E. I. du Pont de Nemours & Company, of Wilmington, Delaware), are often used to diminish the enclosure size requirement. Unfortunately, however, because of these materials' low acoustic absorption, the use of these materials can not substantially reduce the size of the enclosure and simultaneously ensure a balanced low frequency response.
- Furthermore, because conventional acoustic damping materials do not efficiently absorb the acoustic energy during speaker operation, the enclosure absorbs it, and subsequently releases it in the form of acoustic energy at different undesired frequencies, including, possibly, undesirable harmonics of desirable acoustic frequencies.
- Acoustic damping materials can also be useful for absorbing sound in substantially enclosed spaces, such as sound recording rooms and areas that are subject to undesirable noise. One method for absorbing sound includes mounting acoustic damping panels on one or more walls of the enclosed space. However, a disadvantage of conventional acoustic damping materials, which are often made from foamed materials, is that such materials are generally expensive and relatively inefficient.
- It would therefore be desirable to be able to provide an acoustic damping material that can be used whenever acoustic energy is desirably absorbed.
- It would also be desirable to provide an acoustic speaker system that is physically small and produces a broad balanced response over the entire audible spectrum, especially at low frequencies.
- It would further be desirable to be able to provide an acoustic damping material that efficiently absorbs acoustic energy for improving the accuracy of the acoustic reproduction of electric signals of an acoustic speaker system.
- It would be even further desirable to be able to provide an inexpensive, yet highly efficient, acoustic damping panel for absorbing acoustic energy in substantially enclosed spaces.
- It is an object of this invention to provide an acoustic damping material that can be used whenever acoustic energy is desirably absorbed.
- It is also an object of this invention to provide a speaker system that is physically small and produces a broad balanced response over the entire audible spectrum, especially at low frequencies.
- It is a further object of this invention to provide an acoustic damping material that efficiently absorbs acoustic energy for improving the accuracy of the acoustic reproduction of electric signals of an acoustic speaker system.
- It is yet a further object of this invention to provide an inexpensive, yet highly efficient, acoustic damping panel for absorbing acoustic energy in substantially enclosed spaces.
- These objects are achieved with the features of the claims.
- In accordance with this invention, there is provided an acoustic damping material, which includes at least one resilient sheet. Each sheet has a first side and a second side. At least a first portion of one of the first and second sides and a second portion of one of the first and second sides face each other to form a multi-layered structure. The resilient sheet consists of a polyolefin, and more particularly may comprise polyethylene. The sheet preferably has a thickness of less than about 5 mils (about 0.13 mm), and most preferably has a thickness of less than about 1.5 mils (about 0.038 mm).
- The acoustic damping material of this invention may be used to make an acoustic speaker system with an exceptionally flat frequency response. An acoustic speaker system according to this invention at least includes a system enclosure, an acoustic speaker mounted to the enclosure, and acoustic damping material (according to this invention) inside the enclosure.
- The acoustic damping material of this invention may also be used to make an acoustic damping panel. The panel includes a frame and acoustic damping material fixed to the frame. The acoustic damping material again includes at least one resilient sheet arranged in a multi-layered fashion.
- The above and other objects and advantages of the invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
- FIG. 1 is a perspective view of a resilient sheet that can be made into acoustic damping material according to this invention;
- FIG. 2 is a perspective view of an illustrative embodiment according to this invention of a folded acoustic damping structure made from the resilient sheet shown in FIG. 1;
- FIG. 3 is a cross-sectional view, taken from line 3-3 of FIG. 2, of the folded acoustic damping structure of FIG. 2;
- FIG. 4 is a perspective view of an illustrative embodiment according to this invention of a folded roll, acoustic damping structure made from the resilient sheet shown in FIG. 1;
- FIG. 5 is a cross-sectional view, taken from line 5-5 of FIG. 4, of the folded roll, acoustic damping structure of FIG. 4;
- FIG. 6 is a perspective view of an illustrative embodiment according to this invention of a rolled acoustic damping structure made from the resilient sheet shown in FIG. 1;
- FIG. 7 is a cross-sectional view, taken from line 7-7 of FIG. 6, of the rolled acoustic damping structure of FIG. 6;
- FIG. 8 is a perspective view of an illustrative embodiment according to this invention of a hybrid acoustic damping structure made from the resilient sheet shown in FIG. 1;
- FIG. 9 is a cross-sectional view, taken from line 9-9 of FIG. 8, of the hybrid acoustic damping structure of FIG. 8;
- FIG. 10 is a perspective view of an illustrative embodiment according to this invention of a twisted acoustic damping structure made from the resilient sheet shown in FIG. 1;
- FIG. 11 is a cross-sectional view, taken from line 11-11 of FIG. 10, of the twisted acoustic damping structure of FIG. 10;
- FIG. 12 is a cross-sectional view of a first preferred embodiment of an acoustic speaker system constructed according to this invention;
- FIG. 13 is a cross-sectional view, taken from line 13-13 of FIG. 12, of the acoustic speaker system of FIG. 12;
- FIG. 14 is a cross-sectional view, taken from line 14-14 of FIG. 12, of the acoustic speaker system of FIGS. 12 and 13;
- FIG. 15 is a cross-sectional view of a second preferred embodiment of an acoustic speaker system constructed according to this invention;
- FIG. 16 is a perspective view of a preferred embodiment of a acoustic damping panel constructed according to this invention; and
- FIG. 17 is a cross-sectional view, taken from line 17-17 of FIG. 16, of the acoustic damping panel of FIG. 16.
-
- The present invention is directed to an acoustic damping material. When used in an acoustic speaker system, the material provides an exceptionally flat frequency response, especially at low frequencies.
- The acoustic damping material of this invention is made from at least one resilient sheet, which is preferably arranged to form a multi-layered acoustic damping structure. The resilient sheet consists of a polyolefin. Preferably, the polyolefin is polyethylene. The sheet preferably has a thickness of less than about 5 mils (about 0.13 mm), and most preferably has a thickness of less than about 1.5 mils (about 0.038 mm).
- The resilient sheet has a first side and a second side. At least a first portion of one of said first and second sides and a second portion of one of said first and said second sides face each other to form a multi-layered structure.
- There are various ways that one or more sheets may be deformed to create a multi-layered structure. For example, a sheet may be folded, rolled, twisted, or simply crushed with no particular regularity. Also, two or more sheets may be rolled, folded, or twisted together if desired. However, regardless of the method used, pockets, or strata, of a compressible material (e.g., air) are located between adjacent layers.
- Resilient multi-layered structures have been shown to have unusually high acoustic opacity. The high acoustic opacity of these multi-layered structures is believed to result from a combination of the high compressibility of the air pockets and the resilient nature of the individual sheets. Also, the acoustic opacity of the material is improved when a large number of layers is used and when those layers are oriented substantially perpendicular to the acoustic waves being blocked.
- It will be appreciated that the sheets used to make the acoustic damping material of this invention are entirely different from known fibrous acoustic damping materials. Sheets may form flexible barriers that may force incident air in a direction that preferably is substantially perpendicular to the direction of the incident sound wave. Although fibers, to some degree, also redirect sound waves, fibers do not form highly flexible barriers to the passage of sound waves.
- The acoustic damping material of this invention may be used to make an acoustic speaker system with an exceptionally flat frequency response, especially at low frequencies. Such a system includes a system enclosure, an acoustic speaker mounted to the enclosure, and acoustic damping material (made according to this invention) inside the enclosure. Any number of acoustic damping structures can be used inside the enclosure. Preferably, the acoustic damping material is deformed to have a cavity that is adapted to receive the rear side of the speaker.
- In addition to acoustic speaker systems, the acoustic damping material made according to this invention can be used to make other types of acoustic damping structures, such as acoustic damping panels. An acoustic damping panel at least includes a frame and acoustic damping material according to this invention that is fixed to the frame. The surface area of the panel may be increased by constructing a frame that is not flat.
- The invention will now be described with reference to FIGS. 1-17.
- FIG. 1 shows
resilient sheet 100 that may be used to make an acoustic damping material in accordance with this invention.Sheet 100 is preferably deformed as described below to create a multi-layered acoustic damping structure. Alternatively, two or more sheets may be used together to create a multi-layered structure in accordance with this invention. - Resilient sheets are preferably made from any substantially resilient polymer, which may include one or more copolymers. One type of polymer that can be used in accordance with this invention is a polyolefin. Preferably, the polyolefin is polyethylene. A single sheet can have a substantially uniform composition, but can also be a laminate -- i.e., a plurality of substantially parallel layers whose adjacent surfaces are substantially bonded together. A resilient sheet used to make the acoustic damping material according to this invention preferably has a thickness of less than about 5 mils (about 0.13 mm), and most preferably has a thickness of less than about 1.5 mils (about 0.038 mm). A resilient sheet used to make the acoustic damping material according to this invention may be substantially nonporous to air at about atmospheric pressure (i.e., about 1 atm (about 101.3 kPa)).
- Examples of resilient sheets include plastic wraps sold under the trademarks Handi-Wrap®, by DowBrands L.P., of Indianapolis, Indiana and Franklin Wrap™, by Franklin Industries, L.L.C., of Brooklyn, New York. Other examples include Clear Food Wrap, by Pathmark Stores, Inc., of Woodbridge, New Jersey, Saran Wrap, by DowBrands L.P., Indianapolis, Indiana, Reynolds® Plastic Wrap, by Reynolds Metals Company, of Richmond, Virginia, and Glad® Cling Wrap, by First Brands Corporation, of Danbury, Connecticut.
-
Resilient sheet 100 has two sides. Acoustic damping material according to this invention can include one or more sheets, each of which have a first side and a second side. At least a first portion of one of the first and second sides and a second portion of one of the first and second sides face each other to form a multi-layered structure. For example, this means that different portions of (1) one side of one sheet, (2) opposite sides of one sheet, or (3) sides of two different sheets, may face each other. Preferably,single sheet 100 is deformed into a multi-layered structure. - FIG. 2 shows one embodiment of this invention in which
sheet 100 is folded to produce foldedstructure 110. As best shown in FIG. 3, which is a cross-sectional view ofstructure 110,portions 102 and 104 (both of which are portions of a first side of sheet 100), as well as 116 and 118 (both of which are portion of a second side of sheet 100), face each other. In this embodiment, both portions in any one pair of facing portions are from the same side ofsheet 100, with alternating pairs being from different sides ofsheet 100. - There are various other ways that
sheet 100 can be used to make an acoustic damping material according to this invention. A first way includes repeatedly foldingsheet 100 to produce flattenedroll structure 120, shown in FIG. 4. FIG. 5 shows a cross-sectional view ofstructure 120, including particularlyportions 122 and 124 (both of which are portions of one side of sheet 100), which face each other, as well asportions 126 and 128 (each of which is a portion of a different side of sheet 100), which also face each other. For the most part, except for the internal fold whereportions sheet 100 face each other, on this embodiment every pair of facing portions includes one portion from each side ofsheet 100.Air 109, or any other highly compressible material, is located between the facing portions. - A second way that
sheet 100 can be deformed includes simply rolling it intoroll 130, which is shown in FIG. 6. FIG. 7 shows a cross-sectional view ofroll 130, including particularlyportions 132 and 134 (each of which is a portion of a different side of sheet 100), which also face each other. In this embodiment, except for the very center of the roll, every pair of facing portions includes one portion from each side ofsheet 100. Again,air 129, or any other compressible material (e.g., gas), substantially fill the space between facing portions. - A third way that
sheet 100 can be deformed includes both folding and rolling it to createhybrid structure 140, as shown in FIG. 8.Structure 140 includes adjacent layers that face each other (see, e.g., FIG. 9,portions 142 and 144), which are substantially separated by layers of a compressible material (even though facing portions may be in physical contact). In this embodiment, there is a mixture of (1) pairs of facing portions in which each portion is from the same side ofsheet 100, and (2) pairs of facing portions in which one facing portion is from each side ofsheet 100. Acoustic damping material according to any of the embodiments shown in FIGS. 1-11 can also be deformed by twisting one or more sheets into twisted structure 150, as shown in FIGS. 10 and 11. - It will be appreciated that multiple sheets may be used in any number of ways to form multi-layered structures. For example, although
structure 130 is formed by rolling a single sheet, it will be appreciated that two or more sheets may be rolled together if desired. Also, as described above, regardless of the method used to form the multi-layered structure, pockets of air (or any other compressible material) are substantially trapped between the layers. It should be noted, however, that at least some of the pockets are in fluid communication with one another so that the air can travel therebetween. Furthermore, the pockets may be in fluid communication with the atmosphere through one or more ports in the enclosure. - While not wishing to be bound by any particular theory, the unusually high acoustic opacity of these multi-layered structures is believed to result from a combination of the high compressibility of the air pockets and the highly resilient nature of the individual layers. Accordingly, it is believed that the air pressure between the layers should not be substantially different from the atmospheric pressure during operation of the acoustic damping material. When the air pressure between adjacent layers (i.e., in the pockets) is substantially different from atmospheric pressure, that difference may increase the acoustic coupling between adjacent layers, which in turn may decrease the acoustic damping efficiency of the material. Also, the acoustic opacity of the material is improved when a large number of layers, each of which may be formed from the same or different sheets, is used and when those layers are oriented substantially perpendicular to the acoustic waves being blocked.
- The acoustic damping material of this invention may be used to make an acoustic speaker system with an exceptionally flat frequency response, especially at low frequencies. An acoustic speaker system constructed according to this invention also exhibits excellent dynamic response, including a 20% improvement in attack rate and a 30% improvement in decay rate over similar speaker systems using conventional acoustic damping material.
- An acoustic speaker system according to this invention includes a system enclosure, an acoustic speaker mounted to the enclosure, and acoustic damping material made according to this invention inside the enclosure. The acoustic damping material used in this system is the same as described above. Additional acoustic components, such as enclosure ports for providing fluid communication between the acoustic damping material and the atmosphere and additional acoustic speakers, may also be added to the acoustic speaker system as desired.
- FIG. 12 shows a cross-sectional view of
acoustic speaker system 200, which is constructed according to the principles of this invention.Acoustic speaker system 200 includes preferablyspherical enclosure 210, speaker 220, and acoustic dampingmaterial 230. Acoustic dampingmaterial 230 includes one type of acoustic damping structure 232, although any number of acoustic damping structures can be used, as described below. Acoustic dampingmaterial 230 can be formed from one or more resilient sheets. These sheets can then be deformed into at least one multi-layered structure, such as the elongated structures shown in FIGS. 2-11. - Acoustic damping
material 230, which is insideenclosure 210 and behind acoustic speaker 220, may be placed inenclosure 210 in any way. For example,material 230 may simply be loaded intoenclosure 210 with no particular arrangement (not shown), or in any desired arrangement. In a particularly preferred arrangement,material 230 may be wrapped in a spiral fashion as shown in FIGS. 12-14. As shown best in FIG. 12, acoustic dampingmaterial 230 can be deformed into a sphericalstructure having cavity 236, which hassurface 237 that substantially conforms to, or adapted to receive,rear side 221 of acoustic speaker 220. Thus, whenrear side 221 has a conical shape,material 230 can be adapted (e.g., toroidally wrapped) to receive that rear side. Also,enclosure 210 can have other shapes. Ifenclosure 210 were cubical, for example, acoustic dampingmaterial 230 would preferably be deformed to have a substantially cubical shape, but the cavity would still be adapted to received the conicalrear side 221 of speaker 220. - TABLES I and II compare the frequency responses of two types of acoustic speaker systems. The first type of system was structurally substantially identical to
system 200, but used conventional acoustic damping material (i.e., fiberglass wool). The second type of system wassystem 200, which used an acoustic damping material according to this invention (i.e., polyolefine film). The acoustic speaker systems included a 12" (30,48cm) diameter spherical enclosure and a 6" (15,24cm) diameter woofer (effective enclosure volume was about 0.47 ft3 (ca. 0,0133 m3). TABLE I lists experimental results obtained using a sealed enclosure and TABLE II lists experimental results obtained using a ported enclosure.SEALED 12" (30,48 cm) Spherical Enclosure with 6" (15,24 cm) Woofer Frequency (Hz) Response (dB) using Fiberglass wool Response (dB) using Polyethylene film 100 74 74 90 73 75 80 69 76 70 73 77 60 71 76 50 65 72 40 65 72 30 56 65 20 48 60 PORTED 12" (30,48 cm) Spherical Enclosure with 6- (15,24cm) Woofer Frequency (Hz) Response (dB) using Fiberglass wool Response (dB) using Polyethylene film 100 74 74 90 73 73 80 69 70 70 74 74 60 71 72 50 73 75 40 78 75 30 68 72 20 49 65 - Tables I and II reveal that the frequency responses of both the sealed and ported acoustic speaker systems, respectively, are dramatically improved, especially at the low end of the frequency range (i.e., between about 20 Hz and about 50 Hz). And, in the case of the sealed system, the improved frequency response is apparent at even higher frequencies (i.e., up to about 90 Hz). Moreover, while the resonant frequencies of both acoustic systems were identical (i.e., about 57 Hz), the Q values of those resonances in the systems filled with polyethylene film (according to this invention) were substantially reduced.
- Other improvements exhibited by the acoustic speaker systems at least partially filled with polyethylene film are not as easily quantifiable. These improvements include better acoustic transparency, clarity, and imaging. It was also noticed that the acoustic damping material of this invention improves electric-acoustic energy conversion efficiency, especially at low electric power levels.
- FIG. 15 shows a cross-sectional view of another
acoustic speaker system 300, which can also be constructed according to this invention. Likeacoustic speaker system 200,system 300 also includesenclosure 310,speaker 320, and acoustic dampingmaterial 330. However, in contrast to acoustic damping material 220, which is used in system 200 (shown in FIG. 12), acoustic dampingmaterial 330, which is used in system 300 (shown in FIG. 15), includes two types of acoustic damping structures. - The first type of acoustic damping structure is deformed into coiled (i.e., toroidal) acoustic damping
structure 332, which is placed adjacent to and behindspeaker 320.Coiled structure 332 is multi-layered and can be made, for example, from one or more of the acoustic damping materials shown in FIGS. 2-11 and described above.Structure 332, as shown in FIG. 15, is made from an elongated roll structure, similar to the one shown in FIGS. 6 and 7. The second type of acoustic damping structure, foldedstructure 334, preferably fills the remainder ofenclosure 310.Structure 334 also is deformed into layers, but the layers ofstructure 334 are preferably formed by folds in the resilient sheet, similar tostructure 110. In bothmulti-layered structures - It will be understood that although
acoustic speaker system 300 shows only two acoustic dampingstructures internal surface 311 and/or the rear side ofacoustic speaker 320. It should also be understood that the particular arrangements of the damping materials shown in FIGS. 12-15 may be altered as desired. - Enclosure
internal surface 311 can have any shape, including substantially ellipsoidal, substantially spherical, substantially cylindrical, substantially polygonal, and any combination thereof, but is preferably substantially spherical. - In addition to acoustic speaker systems, acoustic damping material according to this invention can be used to make other types of acoustic damping structures, such as acoustic damping panels. Acoustic damping panels can be useful for absorbing sound in substantially enclosed spaces, such as sound recording rooms and areas that are subject to undesirable noise.
Acoustic damping panel 400 is shown in FIGS. 16 and 17 and is constructed in accordance with the principles of this invention.Panel 400 includesframe 410 and acoustic dampingmaterial 420, which is preferably fixed to frame 410 by any convenient means, such as staples or adhesive.Material 420 is the same acoustic damping material described above with reference to FIGS. 1-11. Therefore, acoustic dampingmaterial 420 includes at least one resilient sheet and is arranged in a multi-layered fashion. In another embodiment, the frame used to make the acoustic damping panel may not be flat. In that case, the surface area of the panel can be increased. - Thus it is seen that a general purpose acoustic damping material has been provided. In addition to being used in acoustic speaker systems and acoustic damping panels, the acoustic damping material can be used wherever an acoustic damping effect is desirable. One skilled in the art will appreciate that this invention can be practiced by other than the described embodiments, which are presented for purposes of illustration and not for limitation, and this invention is limited only by the claims which follow.
Claims (45)
- An acoustic damping material comprising at least one resilient sheet (100) consisting of a polyolefin film, each of said at least one sheet having a first side and a second side, wherein at least a first portion (102, 104; 122, 124; 132; 142) of one of said first and second sides and a second portion (116, 118; 126, 128; 134; 144) of one of said first and second sides face each other to form a multi-layered structure (110; 120; 130; 140; 150; 332; 334), wherein said first and second portions are partially separated by a compressible material (109, 129), thereby substantially trapping pockets of said compressible material between said first and said second portions, and wherein at least some of said pockets are in fluid communication with one another.
- The acoustic speaker system of claim 1 wherein said sheet has a thickness less than about 5 mils (about 0.13 mm).
- The acoustic speaker system of claim 2 wherein said sheet has a thickness less than about 1.5 mils (about 0.038 mm).
- The acoustic damping material of claim 1 wherein said at least one sheet is a laminate.
- The acoustic damping material of claim 1 wherein said at least one sheet is substantially nonporous to air at about atmospheric pressure.
- The acoustic damping material of claim 1 wherein said polyolefin comprises polyethylene.
- The acoustic damping material of claim 1 wherein said at least one sheet is twisted.
- The acoustic damping material of claim 1 wherein said at least one sheet is folded.
- The acoustic damping material of claim 1 wherein said at least one sheet is rolled.
- The acoustic damping material of claim 1 wherein said multi-layered structure has a cavity (236).
- The acoustic damping material of claim 10 wherein said cavity has a surface (237) that substantially conforms to a rear side (221) of an acoustic speaker (220; 320).
- The acoustic damping material of claim 11 wherein said cavity surface has a substantially conical portion.
- The acoustic speaker system of claim 1 wherein said compressible material is a gas.
- An acoustic speaker system comprising:a system enclosure (210; 310);an acoustic speaker (220; 320) mounted to said enclosure; andacoustic damping material (230; 330) inside said enclosure, said material comprising at least one resilient sheet (100) consisting of a polyolefin film, each of said at least one sheet having a first side and a second side, wherein at least a first portion (102, 104; 122, 124; 132; 142) of one of said first and second sides and a second portion (116, 118; 126, 128; 134; 144) of one of said first and second sides face each other to form a multi-layered structure (110; 120; 130; 140; 150; 332; 334), wherein said first and second portions are partially separated by a compressible material (109, 129), thereby substantially trapping pockets of said compressible material between said first and second portions, and wherein at least some of said pockets are in fluid communication with one another.
- The acoustic speaker system of claim 14 wherein said sheet has a thickness less than about 5 mils (about 0.13 mm).
- The acoustic speaker system of claim 14 wherein said sheet has a thickness less than about 1.5 mils (about 0.038 mm).
- The acoustic speaker system of claim 14 wherein said at least one sheet is a laminate.
- The acoustic speaker system of claim 14 wherein said at least one sheet is substantially nonporous to air at about atmospheric pressure.
- The acoustic speaker system of claim 14 wherein said polyolefin comprises polyethylene.
- The acoustic speaker system of claim 14 wherein said at least one sheet is twisted.
- The acoustic speaker system of claim 14 wherein said at least one sheet is folded.
- The acoustic speaker system of claim 14 wherein said at least one sheet is rolled.
- The acoustic speaker system of claim 14 wherein said structure has a cavity (236).
- The acoustic speaker system of claim 23 wherein said cavity has a surface (237) that substantially conforms to a rear side (221) of said acoustic speaker.
- The acoustic speaker system of claim 24 wherein said cavity surface has a substantially conical portion.
- The acoustic speaker system of claim 14 wherein said compressible material is a gas.
- The acoustic speaker system of claim 14 wherein said enclosure has an internal surface (311), and wherein at least a portion of said at least one sheet is substantially parallel to at least a portion of said enclosure internal surface.
- The acoustic speaker system of claim 27 wherein said enclosure internal surface has a shape selected from the group consisting of substantially ellipsoidal, substantially spherical, substantially cylindrical, substantially polygonal, and combinations thereof.
- A method for making acoustic damping material, for use in making an acoustic speaker system (200), said method comprising deforming at least one resilient sheet (100) consisting of a polyolefin film, each of said at least one sheet having a first side and a second side, wherein at least a first portion (102, 104; 122, 124; 132; 142) of one of said first and second sides and a second portion (116, 118; 126, 128; 134; 144) of one of said first and second sides face each other to form a multi-layered structure (110; 120; 130; 140; 150; 332; 334), wherein said first and second portions are partially separated by a compressible material (109, 129), thereby substantially trapping pockets of said compressible material between said first and second portions, and wherein at least some of said pockets are in fluid communication with one another.
- The method of claim 29 wherein said deforming comprises deforming by twisting, folding, rolling, and any combination thereof.
- The method of claim 30 wherein said speaker system comprises an enclosure (210; 310), said enclosure having an inner surface (311) and said damping material having a layer density, said density near said inner surface being less than said density remote from said inner surface.
- The method of claim 30 wherein said deforming comprises deforming said at least one sheet so that a cavity (236) is formed therein, said cavity having a surface that substantially conforms a rear side (221) of an acoustic speaker (220; 320).
- The method of claim 29 wherein said deforming comprises deforming at least one sheet that has a thickness less than about 5 mils (about 0.13 mm).
- The method of claim 33 wherein said deforming comprises deforming at least one sheet that has a thickness less than about 1.5 mils (about 0.038 mm).
- The method of claim 34 wherein said deforming comprises deforming at least one sheet that is substantially nonporous to air at about atmospheric pressure.
- The method of claim 29 wherein said deforming comprises deforming at least one sheet that comprises a polymer.
- An acoustic damping panel comprising:a frame (410); andacoustic damping material (420) fixed to said frame, said material comprising at least one resilient sheet (100) consisting of a polyolefin film, each of said at least one sheet having a first side and a second side, wherein at least a first portion (102, 104; 122, 124; 132; 142) of one of said first and second sides and a second portion (116, 118; 126, 128; 134; 144) of one of said first and second sides face each other to form a multi-layered structure (110; 120; 130; 140; 150; 332; 334), wherein said first and second portions are partially separated by a compressible material (109, 129), thereby substantially trapping pockets of said compressible material between said first and second portions, and wherein at least some of said pockets are in fluid communication with one another.
- The acoustic damping panel of claim 37 wherein said sheet has a thickness less than about 5 mils (about 0.13 mm).
- The acoustic damping panel of claim 38 wherein said sheet has a thickness less than about 1.5 mils (about 0.038 mm).
- The acoustic damping panel of claim 37 wherein said at least one sheet is substantially nonporous to air at about atmospheric pressure.
- The acoustic damping panel of claim 37 wherein said polyolefin comprises polyethylene.
- The acoustic damping material of claim 1 wherein at least one of said pockets is in fluid communication with atmosphere.
- The acoustic speaker system of claim 14 wherein at least one of said pockets is in fluid communication with atmosphere.
- The method of claim 29 wherein at least one of said pockets is in fluid communication with atmosphere.
- The acoustic damping panel of claim 37 wherein at least one of said pockets is in fluid communication with atmosphere.
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US09/092,616 US6073723A (en) | 1998-06-05 | 1998-06-05 | Acoustic damping material |
US92616 | 1998-06-05 | ||
PCT/US1999/011726 WO1999063786A1 (en) | 1998-06-05 | 1999-05-27 | Acoustic damping material |
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ATE275808T1 (en) * | 1999-07-20 | 2004-09-15 | Florian Meinhard Koenig | HEADPHONES WITH ADJUSTABLE LOCATION OF THE SOUND EVENT IT GENERATES |
US8107207B2 (en) * | 2008-08-08 | 2012-01-31 | Surge Suppression Incorporated | Potted electrical circuit with protective insulation |
AU2010310736B2 (en) * | 2009-10-20 | 2015-03-05 | Deshum Medical, Llc | Integrated positive airway pressure apparatus |
US8857559B2 (en) * | 2011-06-14 | 2014-10-14 | Chris Reviel | Speaker cabinet and method for fabrication |
US9579745B2 (en) * | 2012-08-29 | 2017-02-28 | Apple Inc. | Systems and methods for enhancing performance of a microphone |
CN104185103A (en) * | 2013-05-21 | 2014-12-03 | 宝德科技股份有限公司 | Earphone |
US9635455B2 (en) * | 2013-09-11 | 2017-04-25 | Sound Solutions International Co., Ltd. | Speaker with grained zeolite material in deep-drawn foil resonance volume |
US10212519B2 (en) | 2015-11-19 | 2019-02-19 | The Lovesac Company | Electronic furniture systems with integrated internal speakers |
US11689856B2 (en) | 2015-11-19 | 2023-06-27 | The Lovesac Company | Electronic furniture systems with integrated induction charger |
US11832039B2 (en) | 2021-04-12 | 2023-11-28 | The Lovesac Company | Tuning calibration technology for systems and methods for acoustically correcting sound loss through fabric |
US11178487B2 (en) | 2015-11-19 | 2021-11-16 | The Lovesac Company | Electronic furniture systems with integrated induction charger |
US10236643B2 (en) | 2015-11-19 | 2019-03-19 | The Lovesac Company | Electrical hub for furniture assemblies |
US10979241B2 (en) * | 2015-11-19 | 2021-04-13 | The Lovesac Company | Electronic furniture systems with integrated artificial intelligence |
US11178486B2 (en) | 2015-11-19 | 2021-11-16 | The Lovesac Company | Modular furniture speaker assembly with reconfigurable transverse members |
US11626094B2 (en) * | 2020-03-03 | 2023-04-11 | Toyota Motor Engineering & Manufacturing, Inc. | Membrane acoustic absorber |
US11647840B2 (en) | 2021-06-16 | 2023-05-16 | The Lovesac Company | Furniture console and methods of using the same |
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US2941911A (en) * | 1955-11-15 | 1960-06-21 | Du Pont | Method of forming continuous structures of polytetrafluoroethylene |
US3386527A (en) * | 1965-08-05 | 1968-06-04 | Daubert Chemical Co | Adhesive sound damping tape for application to vibrating panels |
US3592290A (en) * | 1967-11-21 | 1971-07-13 | James C Armstrong | Speaker cabinet enclosure and method of making same |
JPS5151926A (en) * | 1974-11-01 | 1976-05-07 | Sansui Electric Co | Supiikasochi |
FR2372566A1 (en) * | 1976-11-25 | 1978-06-23 | 3A Art Acoustique Appliquee Sa | Twin-speaker loudspeaker cabinet - is constructed with woofer mounted in front wall and tweeter mounted in secondary front wall |
US4101736A (en) * | 1977-03-17 | 1978-07-18 | Cerwin Vega, Inc. | Device for increasing the compliance of a speaker enclosure |
US4439644A (en) * | 1981-11-24 | 1984-03-27 | Edmund M. Jaskiewicz | Loud speaker enclosure |
US4485275A (en) * | 1982-03-25 | 1984-11-27 | Lahti Uolevi L | Inverted horn loudspeaker |
SE450656B (en) * | 1982-05-14 | 1987-07-13 | Bahco Ventilation Ab | Muffler for ventilation ducts or ventilation equipment |
DE3733284C2 (en) * | 1987-10-02 | 1994-08-11 | Helmut Pelzer | Process for the production of a front wall covering for automobiles |
JPH0622890B2 (en) * | 1989-11-20 | 1994-03-30 | チッソ株式会社 | Three-layer polymer material rolled plate and method for producing the same |
JPH0617066B2 (en) * | 1989-12-11 | 1994-03-09 | 新日本製鐵株式会社 | Three-layer polymer material rolled plate and method for producing the same |
JPH1061057A (en) * | 1996-08-19 | 1998-03-03 | Sekisui Chem Co Ltd | Vibration-damping sheet for folded plate roof and folded plate roof |
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